This invention relates generally to aseptic liquid filling and more particularly relates to process and apparatus for providing a HEPA air shower to the critical fill or filling zone of a liquid filling operation, such as for example a blow-fill-sealing operation, to prevent entry of particulate, non-viable and viable particulate, into the critical filling zone. Further, particularly, this invention relates to process and apparatus for providing such HEPA air shower in the form of a single or opposed dual laminar, or at least substantially laminar, flow or flows of pressurized HEPA air.
Numerous patents disclose methods and apparatus for forming, such as by blow molding, filling such as with a liquid, and sealing a container containing the liquid. Note for example, U.S. Pat. Nos. 3,251,915; 3,464,085; 3,523,401; 3,597,793; 3,664,793; 3,674,405; 3,719,374; 4,176,153; 4,178,976; 4,997,014 and U.S. Pat. No. Re. 27,155; and patents cited therein.
As generally known to those skilled in the art, the blow-fill-sealing process is an automated process by which plastic containers are formed, filled with liquid, and sealed in one continuous operation. More particularly, and as further known to those skilled in the art, in the blow-fill-sealing process a hollow, cylindrical plastic parison is extruded downwardly between cavities provided in pairs of open and opposed main and sealing molds mounted for reciprocal movement toward and away from each other; the mold cavities are shaped complementarily to the plastic container to be formed. The main molds are then closed around the plastic parison to seal the bottom of the container after which pressurized air, in the blow molding step, is forced into the plastic parison to force the plastic parison outwardly against the walls of the main mold cavities to partially form the container but leaving the container top open for subsequent liquid filling. Thereafter, a liquid fill nozzle is advanced above, or slightly into, the open top of the partially formed plastic container and liquid, such as a sterile liquid, e.g., a pharmaceutical solution, is injected or dispensed into the partially formed plastic container after which the nozzle is withdrawn and the seal molds are closed to seal the upper portion of the container and complete a pre-liquid filled plastic container.
Aside from the economic advantages of the blow-fill-sealing process, such process is a favored process for aseptic filling of sterile liquid products, such as the above-noted pharmaceutical solution, due to the limited need for human intervention in the process, and hence minimal opportunity for microbial or pathogenic microorganism contamination due to human intervention. One limitation, as is also known to those skilled in the art, is that in the blow-fill-sealing process non-viable particulate, or particulate matter or particles, are generated during the extrusion of the plastic parison in the container blow-fill-sealing process noted above. These non-viable particulate can potentially provide the means of transport for viable microorganisms, particularly pathogenic microorganisms, into the partially formed and open plastic container prior to the sealing step. As is still further known to those skilled in the art, in an effort to protect the pre-liquid fill product produced by the blow-fill-sealing process, blow-fill-sealing apparatus or machine have been provided with shrouds at the critical fill or filling zone. The critical filling zone, as known to the art and as used hereinafter and in the appended claims, means the zone immediately surrounding or encompassing the open top of the partially formed plastic container and at least a portion of the liquid fill nozzle, such critical filling zone is shown by the dashed circle in FIG. 1 bearing numerical designation 30; such critical filling zone is sometimes referred to in the art as the fill/nozzle area.
A prior art shroud known to the art for preventing entry of the particulate into the critical filling zone includes a single duct for receiving and communicating a single flow of pressurized high efficiency particulate air (HEPA air) from a single direction to the critical filling zone to prevent entry of particulate to the critical filling zone; such flow of pressurized HEPA air to the critical filling zone is referred to in the art and hereinafter and in the appended claims as a HEPA air shower. It has been found that such flow of pressurized HEPA air provided by prior art process and apparatus is a non-laminar, or at least substantially non-laminar, flow of pressurized HEPA air and it has been found that such flow of pressurized HEPA air can produce vortex, or vortices, in the critical filling zone which vortex, or vortices, can undesirably draw particulate into the critical filling zone.
However, there exists a need in the art for improved process and apparatus for more effectively preventing entry of particulate, non-viable and viable particulate, into the critical filling zone to further enhance aseptic liquid filling of products, such as for example, pre-liquid filled plastic containers produced by the above-noted blow-fill-sealing operation.